It hasn't been that long since we last rounded up the experimental Firefox extensions worth checking out. In the meantime, though, some very small helpers came along and added some clever functionality to the 'fox.

Every so often, Lifehacker rounds up Firefox add-ons that are too new for official approval, but…
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As always with this series, the downloads we're pointing to here are both unapproved by Firefox's maker, Mozilla, and require creating an account or logging into it, because the standard use-at-your-own-risk warnings for unofficial or untested software apply. That said, many experimental extensions are just waiting for a final go-ahead from Mozilla, and can be pretty darned useful.

So this one's not quite "experimental" in the strict sense, as anyone running a beta of Firefox 3.1—er, make that 3.5—can install it without needing a Mozilla account. But Firefox 3.5 is, obviously, beta, and if you're digging its speedier JavaScript, break-away tabs, privacy mode, and much more, whether on your desktop or thumb drive, you should definitely give it a go. The Mozilla team is constantly updating their designs and ideas for the next tab page design, and there's links, recently copied data actions, undo closed tab links, and lots more. If nothing else, you'll be able to feign bored, superior been-there-ness when the next major Firefox update drops.

Intrigued by a JavaScript applet on a favorite web site? Unable to find the text of a page you were just on, and now can't get back to? CacheSearch is like an Everything file searcher for the Firefox cache. Launch it with Ctrl+Shift+S, give it a few seconds to build a database, and then type in the sites or phrases you're looking for. CacheSearch digs around and finds your results as you search, and lets you preview them in a bottom window or open in a browser. Not all that helpful if you've got Firefox set to clean out your cache pretty frequently, but developers and those with a knack for losing things could find this handy.

This one's small, simple, and pretty helpful, especially for research and text wrangling. On its own, Firefox's Ctrl-F-activated word search function can look for one word, and then another, forgetting the first. FindList simply holds up to 15 words in a pop-up menu from that text box. So if you're heading from page to page, looking for two or three words or phrases, you won't have to retype them with FindList installed. That's what it does, and it's precisely why Firefox extensions exist, since one team of developers can't think of every little thing.

Twitter is an of-the-moment, ephemeral type of place—not somewhere you stash the stuff you want to look at later. Still, some of the stuff you link to on the service would be worth getting back to later, and made search-able, right? Tweecious is a simple converter between your Twitter and Delicious bookmarking accounts. The add-on launches you into a preferences page on Tweecious' site, and—here's a novel idea—doesn't ask for any passwords, but checks that you're logged into both services and grabs your username from each. You confirm your usernames, specify a few things (like how many tweets it should roll back through), and then it gets to work. If you used a link-shortener like TinyURL, Bit.ly or whatnot, Tweecious spots them and extends them using the previously mentioned LongURL. For someone who's been pretty active on Twitter, it can be amazing just how many links you've collected to weird, wonderful stuff—for those who really don't care about anything they've linked to on the micro-blog service, well, consider yourself productively lucky, we suppose.